Sean Ono Lennon, 42, and James McCartney, 40, sent social media users into a frenzy after sharing a side-by-side snap resembling their legendary fathers.

The photo left fans emotional after it hinted at the much-adored friendship between the Beatles singers and even left fans optimistic of a future collaboration.

Lennon simply captioned the surprise photograph: “Peekaboo.”

18th July 1968: Fans gushed over the duo's resemblance to their fathers (Photo by Michael Webb/Keystone/Getty Images) (Keystone/Getty Images)

One excited user wrote: “This made my day!!! So love that the Lennon and McCartney families are still tied. Wishing you both all the best. We all would love to hear some music from you-no pressure lol.”

Another commented: “You two definitely look like your famous fathers. I am still saddened by the loss of your father Sean. The world lost a wonderful person.”

A third added: “McLennon of today!!”

Meanwhile another posted: “Wow, y’all look exactly like your dads’ and ‘It’s fun to see Lennon & McCartney again. Best wishes to you both!” [sic]

Other Instagram users hailed the image the “coolest photo ever.”

The snap comes after Paul McCartney took a trip down memory lane by returning to the birthplace of Beatlemania, Liverpool’s Cavern Club, for a secret show.

Last month, McCartney made an official announcement on Twitter, revealing that 200 tickets for the 2pm gig would be available a short walk from the venue, at the Echo arena.

Tickets to the secret show were handed out on a first come, first served basis with around 250 lucky people crammed into the iconic venue.

The 28-song set ranged from iconic Beatles classics, including All My Loving and Lady Madonna, to a reel of new songs from McCartney’s upcoming album Egypt Station.

The 76-year-old’s two-hour set concluded with I Saw Her Standing There, Sgt. Pepper's Lonely Hearts Club Band and Helter Skelter.